milli ohm meter query

[Grant Richter]

One of the desktop Flukes, a 3 1/2 digit has
a 2 ohm and 20 ohm range for this purpose.

----------
> From: patchell <patchell at teletrac.com>
> To: Paul Perry <pfperry at melbpc.org.au>
> Cc: synth-diy at mailhost.bpa.nl
> Subject: Re: milli ohm meter query
> Date: Saturday, February 19, 2000 10:21 PM
> 
> 
> 
> Paul Perry wrote:
> 
> > I'm doing a lot of hunting for shorts on PCBs at the moment.
> > Naturally i can't afford a 'proper' millohm meter (and I only
> > need somethng going up to say 100 millohms full scale.
> >
> > Is there any way I can adapt my cheap digital multimeter for this,
> > with some kind of little external add-on ckt?
> > Accuracy isn't important.
> > It  has a 4 ohm scale.
> >
> > paul perry melbourne australia
> 
>     Paul:
> 
>     I have used a Fluke 8050A for this purpose (4-1/2 digit DVM).  The
> feature it has that makes it nice for tracking down shorts is a little
> button on the front called "relative".  I short the probes together,
> push that little button, and it knocks out the probe resistance.  This
> is not quite as good as a four wire probe, but good enough for tracking
> down the short.  The lowest scale is 200 ohms full scale (same as most
> of the 3-1/2 digit meters), but that extra digit means .01 ohm
> resolution.  This I find good enough for going down the trace looking
> for the lowest resistance.  You still have to be patient, but I have had
> a 100% success rate doing this (just did this only yesterday).
> 
>     Another tool I used once put a very low current pulse on the trace.
> You connected the two circuits that were shorted to this thing, and used
> some sort of probe that would tell you which way the current was
> flowing.  Kind of neat, but in reality, I have had much better luck with
> the 8050a.
> 
>     Just my opinions.
> 
>     -Jim
> 
> 
> 
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